Future of the Colorado River

The once mighty Colorado River, a source of drinking and agricultural water for much of the Southwestern United States is severely threatened by the effects of climate change according to a report by the USGS. Researchers there say that a small temperature increase of about 0.9 degrees Celsius would reduce the average flow of water in the river to its lowest flow in nearly 500 years.

A “modest” 0.86 degree Celsius (1.5 degree Fahrenheit) increase in the 21st century could trim the average flow of the river — the primary water supply for residents in much of the U.S. Southwest — to the low end of a range marked between 1490 and 1998, USGS scientist Gregory McCabe said yesterday.

The Earth is likely to warm by more than twice that amount in the period, Rajendra Pachauri, chairman of the United Nations Intergovernmental Panel on Climate Change, said last month. McCabe will brief Congress on the findings in June, when legislators expect to debate plans for the world’s largest producer of greenhouse gases to begin capping its emissions.

“A 2-degree Celsius warming pushes the risk so high that it’s beyond anything that has happened in the last 500 years,” McCabe said on a conference call yesterday. “The average flow in the Colorado drops to lower than anything we’ve seen.”